The U.S. Education Department is urging the nation's colleges and K-12 schools to guard against harassment and discrimination based on race, religion or national origin, a response to anti-Muslim and anti-refugee sentiments that appear to be on the rise.

"A focus on these protections, while always essential, is particularly important amid international and domestic events that create an urgent need for safe spaces for students," reads the Dec. 31 open letter to school leaders, which was signed both by Arne Duncan, who stepped down as U.S. Education Secretary that day, and John B. King Jr., who is now serving as acting secretary.

The letter described the kind of behavior that schools should look out for, from name-calling to physical attacks, and singled out students who are most likely to need protection: "Those who are, or are perceived to be, Syrian, Muslim, Middle Eastern, or Arab, as well as those who are Sikh, Jewish, or students of color."